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Apple SOS
The Sophisticated Operating System, or SOS (), is the primary operating system of the Apple III computer. SOS was developed by Apple Computer and released in October 1980. In 1985, Steve Wozniak, while critical of the Apple III's hardware flaws, called SOS "the finest operating system on any microcomputer ever". Technical details SOS is a single-tasking single-user operating system. It makes the resources of the Apple III available in the form of a menu-driven utility program as well as a programming application programming interface (API). A single program is loaded at boot time, called the interpreter. Once loaded, the interpreter can then use the SOS API to make requests of the system. The SOS API is divided into four main areas: #File Calls: Create, destroy, rename, open, close, read, write files; set, get prefix (current working directory); set, get file information; get volume information; set, set mark, EOF, and level of files #Device Calls: Get status, device nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergency Call
An emergency telephone number is a number that allows a caller to contact local emergency services for assistance. The emergency number differs from country to country; it is typically a three-digit number so that it can be easily remembered and dialed quickly. Some countries have a different emergency number for each of the different emergency services; these often differ only by the last digit. In many countries, dialing either 112 (used in Europe and parts of Asia, Africa and South America) or 911 (used mostly in the Americas) will connect callers to emergency services. For individual countries, see the list of emergency telephone numbers. Configuration and operation The emergency telephone number is a special case in the country's telephone number plan. In the past, calls to the emergency telephone number were often routed over special dedicated circuits. Though with the advent of electronic exchanges these calls are now often mixed with ordinary telephone traffic, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Write Protection
Write protection is any physical mechanism that prevents writing, modifying, or erasing data on a device. Most commercial software, audio and video on writeable media is write-protected when distributed. Examples * IBM -inch magnetic tape reels, introduced in the 1950s, had a circular groove on one side of the reel, into which a soft plastic ring had to be placed in order to write on the tape. ("No ring, no write.") * Audio cassettes and VHS videocassettes have tabs on the top/rear edge that can be broken off (uncovered = protected). * 8 and -inch floppies can have, respectively, write-protect and write-enable notches on the right side (8-inch punched = protected; -inch covered/notch not present = protected). A common practice with single-sided floppies was to punch a second notch on the opposite side of the disk to enable use of both sides of the media, creating a flippy disk, so called because one originally had to flip the disk over to use the other side. * -inch floppy di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chain Loading
Chain loading is a method used by computer programs to replace the currently executing program with a new program, using a common data area to pass information from the current program to the new program. It occurs in several areas of computing. Chain loading is similar to the use of overlays. Unlike overlays, however, chain loading replaces the currently executing program in its entirety. Overlays usually replace only a portion of the running program. Like the use of overlays, the use of chain loading increases the I/O load of an application. Chain loading in boot manager programs In operating system boot manager programs, chain loading is used to pass control from the boot manager to a boot sector. The target boot sector is loaded in from disk, replacing the in-memory boot sector from which the boot manager itself was bootstrapped, and executed. Chain loading in Unix In Unix (and in Unix-like operating systems), the exec() system call is used to perform chain loadi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apple ProDOS
ProDOS is the name of two similar operating systems for the Apple II of personal computer. The original ProDOS, renamed ProDOS 8 in version 1.2, is the last official operating system usable by all 8-bit Apple II computers, and was distributed from 1983 to 1993. The other, ProDOS 16, was a stop-gap solution for the 16-bit Apple II that was replaced by GS/OS within two years. ProDOS was marketed by Apple as meaning Professional Disk Operating System, and became the most popular operating system for the Apple II 10 months after its release in January 1983. Background ProDOS was released to address shortcomings in the earlier Apple operating system (called simply DOS), which was beginning to show its age. Apple DOS only has built-in support for 5.25" floppy disks and requires patches to use peripheral devices such as hard disk drives and non- Disk-II floppy disk drives, including 3.5" floppy drives. ProDOS adds a standard method of accessing ROM-based drivers on expansion ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel (operating System)
A kernel is a computer program at the core of a computer's operating system that always has complete control over everything in the system. The kernel is also responsible for preventing and mitigating conflicts between different processes. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources (e.g. I/O, memory, cryptography) via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the use of common resources, such as CPU, cache, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup (after the bootloader). It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit. The critical code of the kernel is usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bootloader
A bootloader, also spelled as boot loader or called bootstrap loader, is a computer program that is responsible for booting a computer and booting an operating system. If it also provides an interactive menu with multiple boot choices then it's often called a boot manager. When a computer is turned off, its softwareincluding operating systems, application code, and dataremains stored on non-volatile memory. When the computer is powered on, it typically does not have an operating system or its loader in random-access memory (RAM). The computer first executes a relatively small program stored in the boot ROM, which is read-only memory (ROM, and later EEPROM, NOR flash) along with some needed data, to initialize hardware devices such as CPU, motherboard, memory, storage and other I/O devices, to access the nonvolatile device (usually block device, e.g., NAND flash) or devices from which the operating system programs and data can be loaded into RAM. Some earlier computer systems, u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floppy Disk
A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a fabric that removes dust particles from the spinning disk. The three most popular (and commercially available) floppy disks are the 8-inch, 5¼-inch, and 3½-inch floppy disks. Floppy disks store digital data which can be read and written when the disk is inserted into a floppy disk drive (FDD) connected to or inside a computer or other device. The first floppy disks, invented and made by IBM in 1971, had a disk diameter of . Subsequently, the 5¼-inch (133.35 mm) and then the 3½-inch (88.9 mm) became a ubiquitous form of data storage and transfer into the first years of the 21st century. 3½-inch floppy disks can still be used with an external USB floppy disk drive. USB drives for 5¼-inch, 8-inch, and other-size floppy disks are rare ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as the Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words of 12, 18, 24, 30, 36, 48, or 60 bits, corresponding t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serial Port
A serial port is a serial communication Interface (computing), interface through which information transfers in or out sequentially one bit at a time. This is in contrast to a parallel port, which communicates multiple bits simultaneously in Parallel communication, parallel. Throughout most of the history of personal computers, data has been transferred through serial ports to devices such as modems, computer terminal, terminals, various peripherals, and directly between computers. While interfaces such as Ethernet, FireWire, and USB also send data as a serial Stream (computing), stream, the term ''serial port'' usually denotes Computer hardware, hardware compliant with RS-232 or a related standard, such as RS-485 or RS-422. Modern consumer personal computers (PCs) have largely replaced serial ports with higher-speed standards, primarily USB. However, serial ports are still frequently used in applications demanding simple, low-speed interfaces, such as industrial automation sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Block Device
In Unix-like operating systems, a device file, device node, or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. There are also special files in DOS, OS/2, and Windows. These special files allow an application program to interact with a device by using its device driver via standard input/output system calls. Using standard system calls simplifies many programming tasks, and leads to consistent user-space I/O mechanisms regardless of device features and functions. Overview Device files usually provide simple interfaces to standard devices (such as printers and serial ports), but can also be used to access specific unique resources on those devices, such as disk partitions. Additionally, device files are useful for accessing system resources that have no connection with any actual device, such as data sinks and random number generators. There are two general kinds of device files in Unix-like operating systems, k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
